step_port_forward: add access to localhost if necessary

Fixes #104

For Virtualbox versions >= 7.0, access to the host's network
(via 10.0.2.2) is blocked by default unless the
`--nat-localhostreachableN=on` option is used.

builder/virtualbox/common/step_port_forwarding.go

@@ -7,12 +7,14 @@ import (
 	"context"
 	"fmt"
 	"log"
+	"os"
 	"strings"
 
 	"github.com/hashicorp/packer-plugin-sdk/communicator"
 	"github.com/hashicorp/packer-plugin-sdk/multistep"
 	"github.com/hashicorp/packer-plugin-sdk/net"
 	packersdk "github.com/hashicorp/packer-plugin-sdk/packer"
+	"golang.org/x/mod/semver"
 )
 
 // This step adds a NAT port forwarding definition so that SSH or WinRM is available
@@ -34,6 +36,48 @@ type StepPortForwarding struct {
 	l *net.Listener
 }
 
+var vboxVerMinNeedLHReachable string
+
+func init() {
+	vboxVerMinNeedLHReachable = semver.Canonical("v7.0")
+	if vboxVerMinNeedLHReachable == "" {
+		fmt.Fprintf(os.Stderr, "Constant version is invalid; this is a bug with the VirtualBox plugin, please open an issue to report it.\n")
+		os.Exit(1)
+	}
+}
+
+func addAccessToLocalhost(state multistep.StateBag) error {
+	driver := state.Get("driver").(Driver)
+	vmName := state.Get("vmName").(string)
+
+	vboxVer, err := driver.Version()
+	if err != nil {
+		return fmt.Errorf("Error getting VirtualBox version: %s", err)
+	}
+	if !strings.HasPrefix(vboxVer, "v") {
+		vboxVer = "v" + vboxVer
+	}
+	if !semver.IsValid(vboxVer) {
+		return fmt.Errorf("The VirtualBox version isn't a valid SemVer: %s", vboxVer)
+	}
+
+	vboxVer = semver.Canonical(vboxVer)
+
+	if semver.Compare(vboxVer, vboxVerMinNeedLHReachable) >= 0 {
+		command := []string{
+			"modifyvm", vmName,
+			"--nat-localhostreachable1",
+			"on",
+		}
+		if err := driver.VBoxManage(command...); err != nil {
+			return fmt.Errorf("Failed to configure host's local network as reachable for NAT interface: %s", err)
+		}
+		log.Printf("[TRACE] VirtualBox's version (%q) is >= %q, setting --nat-localhostreachable1 on", vboxVer, vboxVerMinNeedLHReachable)
+	}
+
+	return nil
+}
+
 func (s *StepPortForwarding) Run(ctx context.Context, state multistep.StateBag) multistep.StepAction {
 	driver := state.Get("driver").(Driver)
 	ui := state.Get("ui").(packersdk.Ui)
@@ -80,6 +124,13 @@ func (s *StepPortForwarding) Run(ctx context.Context, state multistep.StateBag)
 			return multistep.ActionHalt
 		}
 
+		// Add the `--nat-localhostreachableN=on` option if necessary
+		if err := addAccessToLocalhost(state); err != nil {
+			state.Put("error", err)
+			ui.Error(err.Error())
+			return multistep.ActionHalt
+		}
+
 		// Create a forwarded port mapping to the VM
 		ui.Say(fmt.Sprintf("Creating forwarded port mapping for communicator (SSH, WinRM, etc) (host port %d)", commHostPort))
 		command = []string{

builder/virtualbox/common/step_port_forwarding_test.go

@@ -0,0 +1,79 @@
+// Copyright (c) HashiCorp, Inc.
+// SPDX-License-Identifier: MPL-2.0
+
+package common
+
+import (
+	"reflect"
+	"testing"
+)
+
+func TestVirtualboxVersionIsAnInValidSemver(t *testing.T) {
+	state := testState(t)
+
+	state.Put("vmName", "foo")
+
+	driver := state.Get("driver").(*DriverMock)
+	driver.VersionResult = "v7.0.0abcd"
+	driver.VersionErr = nil
+
+	err := addAccessToLocalhost(state)
+
+	if err == nil {
+		t.Fatalf("We expected a failure but we got a success!")
+	}
+}
+
+func TestVirtualboxVersionNeedsLocalhostAccessFlag(t *testing.T) {
+	const versionRequiringFlag = "v7.0"
+	const vmName = "foo"
+
+	state := testState(t)
+
+	state.Put("vmName", vmName)
+
+	driver := state.Get("driver").(*DriverMock)
+	driver.VersionResult = versionRequiringFlag
+	driver.VersionErr = nil
+
+	err := addAccessToLocalhost(state)
+
+	if err != nil {
+		t.Fatalf("Unexpected failure with VBox version '%v': %v", versionRequiringFlag, err)
+	}
+
+	if len(driver.VBoxManageCalls) == 0 {
+		t.Fatal("VBoxManage wasn't called!")
+	} else if len(driver.VBoxManageCalls) > 1 {
+		t.Fatalf("Expected VBoxManage to be called once, but it was called %v times!", len(driver.VBoxManageCalls))
+	}
+
+	expectedArgs := []string{"modifyvm", vmName, "--nat-localhostreachable1", "on"}
+	args := driver.VBoxManageCalls[0]
+	if !reflect.DeepEqual(args, expectedArgs) {
+		t.Fatalf("Expected VBoxManage to be called with arguments %v, but it was called with arguments %v!", expectedArgs, args)
+	}
+}
+
+func TestVirtualboxVersionDoesNotNeedLocalhostAccessFlag(t *testing.T) {
+	const versionNotRequiringFlag = "v6.9"
+	const vmName = "foo"
+
+	state := testState(t)
+
+	state.Put("vmName", vmName)
+
+	driver := state.Get("driver").(*DriverMock)
+	driver.VersionResult = versionNotRequiringFlag
+	driver.VersionErr = nil
+
+	err := addAccessToLocalhost(state)
+
+	if err != nil {
+		t.Fatalf("Unexpected failure with VBox version '%v': %v", versionNotRequiringFlag, err)
+	}
+
+	if len(driver.VBoxManageCalls) != 0 {
+		t.Fatalf("Expected VBoxManage not to be called, but it was called %v times!", len(driver.VBoxManageCalls))
+	}
+}

go.mod

@@ -9,6 +9,7 @@ require (
 	github.com/hashicorp/packer-plugin-sdk v0.5.2
 	github.com/stretchr/testify v1.8.3
 	github.com/zclconf/go-cty v1.13.3
+	golang.org/x/mod v0.13.0
 )
 
 require (

go.sum

@@ -346,6 +346,8 @@ golang.org/x/mobile v0.0.0-20210901025245-1fde1d6c3ca1 h1:t3ZHqovedSY8DEAUmZA99f
 golang.org/x/mobile v0.0.0-20210901025245-1fde1d6c3ca1/go.mod h1:jFTmtFYCV0MFtXBU+J5V/+5AUeVS0ON/0WkE/KSrl6E=
 golang.org/x/mod v0.1.0/go.mod h1:0QHyrYULN0/3qlju5TqG8bIK38QM8yzMo5ekMj3DlcY=
 golang.org/x/mod v0.4.2/go.mod h1:s0Qsj1ACt9ePp/hMypM3fl4fZqREWJwdYDEqhRiZZUA=
+golang.org/x/mod v0.13.0 h1:I/DsJXRlw/8l/0c24sM9yb0T4z9liZTduXvdAWYiysY=
+golang.org/x/mod v0.13.0/go.mod h1:hTbmBsO62+eylJbnUtE2MGJUyE7QWk4xUqPFrRgJ+7c=
 golang.org/x/net v0.0.0-20180724234803-3673e40ba225/go.mod h1:mL1N/T3taQHkDXs73rZJwtUhF3w3ftmwwsq0BUmARs4=
 golang.org/x/net v0.0.0-20180826012351-8a410e7b638d/go.mod h1:mL1N/T3taQHkDXs73rZJwtUhF3w3ftmwwsq0BUmARs4=
 golang.org/x/net v0.0.0-20181114220301-adae6a3d119a/go.mod h1:mL1N/T3taQHkDXs73rZJwtUhF3w3ftmwwsq0BUmARs4=